A video game device is exemplified as an entertainment system. In the entertainment system such as a video game device, an optical disk such as a CD-ROM and a DVD-ROM, for example, is used as a recording medium in which a game program is recorded. Video (image) information and audio (voice) information constituting a game is recorded in such an optical disk. In general, a content of the image information is significantly large. Thus, it is not practical to record the image information in the optical disk as it is.
Therefore, image data is coded and compressed for recording in the optical disk.
In order to load into the video game device the optical disk with compressed image data recorded and to reproduce the image data recorded in the optical disk, it is necessary for a game device body to decode (expand) the compressed image data. Conventionally, such a decoding unit is provided within the game device body as hardware units. The decoding unit is also technically improved rapidly as well as other technologies.
However, as described above, if the decoding unit is configured by hardware units, it becomes harder to update/improve the decoding unit in accordance with an advance of the decoding technology. Thus, it could be considered that the decoding means is programmed and configured by software means so that it can be reprogrammed anytime. However, if the whole decoding unit is configured by software means, its processing time tends to increase as compared with one configured by hardware units, generally.
In the case of the video game device, data to be recorded in the optical disk is compressed before the optical disk is provided to a user (game player), and the decoding is done by a game device manufacturer or a game software manufacturer. Thus, time required for compressing data to be recorded in the optical disk is not such a big problem.
On the other hand, the compressed data must be decoded (expanded) from the optical disk while the game is executed and enjoyed by a user. Then, the required time for decoding (expanding) the compressed data becomes a critical matter and real time processing is demanded.